1. Field of the Invention
The present invention generally relates to a medical device for embolic protection.
2. Description of Related Art
With the continuing advance of medical techniques, interventional procedures are more commonly being used to actively treat stenosis, occlusions, lesions, or other defects within a patient's blood vessels. Often the treated regions are in the coronary, carotid or even cerebral arteries. One procedure for treating an occluded or stenosed blood vessel is angioplasty. During angioplasty, an inflatable balloon is introduced into the occluded region. The balloon is inflated, pushing against the plaque or other material of the stenosed region and increasing the intralumenal diameter of the vessel. As the balloon presses against the material, portions of the material may inadvertently break free from the plaque deposit. These emboli may travel along the vessel and become trapped in a smaller blood vessel restricting blood flow to a vital organ, such as the brain.
Other methods for removing plaque or thrombus from arteries may include mechanical ablation, or non-contact ablation using light waves, sound waves, ultrasonics, or other radiation. Each of these methods are subject to the risk that some thrombogenic material may dislodge from the wall of the vessel and occlude a smaller blood vessel. The occlusion may cause damage to the patient, including an ischemic stroke in the cerebral arteries.
To prevent the risk of damage from emboli, many devices have been used to restrict the flow of emboli downstream from the stenosed area. One method includes inserting a balloon that may be expanded to occlude the flow of blood through the artery downstream of the stenosed area. An aspirating catheter may be located between the balloon and stenosed area and used to remove emboli that may be caused by the treatment. However, because the balloon completely blocks blood flow through the vessel, the vessel may be occluded only for short periods of time, limiting use of the procedure.
As an alternative to occluding flow through the blood vessel, various filtering devices have been proposed. Such devices typically have elements that form legs or a mesh that capture embolic material, but allow blood cells to flow between the elements. Capturing the emboli in the filter device prevents the material from being lodged downstream in a smaller blood vessel. The filter may then be removed along with the embolic material after the procedure has been performed and the risk from emboli has decreased.
Challenges also exist with filtering devices. Often it is desirable to deploy filter devices from the proximal side of a stenosis. Therefore, the profile of the filtering device should be smaller than the opening in the stenosed vessel. Further, the smaller the profile of the filtering device the less risk of dislodging emboli during deployment of the device. In addition, if the filter portion is not held against the inside of the vessel wall, there is a risk that embolic material may pass between the filter and the vessel wall. The filter portion should also be durable and firmly secured to the medical device, since any damage caused to the medical device during deployment increases the risk that emboli might breach the medical device.
In view of the above, it is apparent that there exists a need for an improved medical device for embolic protection.